Bear behavior changes from location to location, season to season and year to year depending on lots of different factors. If you are going to be hiking in bear country take the time to talk to biologists in the area to find out what kind of year they are having. If it is really early in the season they are just coming out of hibernation and eating a more vegetarian diet generally, but once they have been out of their dens for a few weeks their appetite starts to gear up and they may become more aggressive over a kill, or more assertive toward easy pickings. If food is on time and abundant they tend to be a little more laid back, but if their traditional food sources are late even by as little as a week, they can get really grumpy.

Bottom line, if you aren't used to hiking in bear country take the time to do your homework and learn as much as you can about the behavior of the bears that inhabit the area.